the splicers are talking about Jack. Basically they are saying that Jack went to the surface with some little sisters and that now that Ryan is gone, Dr. Lamb is their new leader.

These posters are found in the level “Siren Alley”. The hands have Jack’s chain tattoo on both wrists. If you turn around and go up the stairs there is a picture of the plane sinking? and the lighthouse.

In BioShock 1 the character you were playing is jack. At the of BioShock 1 you had a note saying “Would you kindly take the plane down”. You also had to walk through the back end of the plane in the waterway tunnel after you get your first plasmid. So the back end of the plane must have fell off the waterway tunnel to the bottom of the ocean. at the end of the plane there is a large A (you might have to turn on the brightness of the game to see it). The same sign and in the same place was in jack’s plane in BioShock 1.